<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name = 'viewport' content="">
    <title>promise 测试</title>
</head>
<body>
    <script>
        var promise = new Promise(function (resolve, reject) {
            resolve(10)
        })
        var p1 = promise.then(function (value) {
            console.log(value)
            return p1
        })
        p1.then(() => {}, function (reason) {
            console.log(reason)
        })
    </script>
</body>
</html>